feat: complete analytics module self-containment

Migrate analytics module to fully self-contained structure:

- routes/api/vendor.py - API endpoints
- routes/pages/vendor.py - Page routes with full implementation
- services/stats_service.py - Business logic (moved from app/services)
- services/usage_service.py - Usage tracking (moved from app/services)
- schemas/stats.py - Pydantic schemas (moved from models/schema)
- models/__init__.py - Model exports
- templates/analytics/vendor/ - Templates (moved from app/templates)
- static/vendor/js/ - JavaScript (moved from static/vendor)
- locales/ - Translations (en, de, fr, lu)
- exceptions.py - Module exceptions

Removed legacy files:
- app/modules/analytics/routes/vendor.py (replaced by routes/pages/)
- static/admin/js/analytics.js (unused)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/analytics/locales/de.json

@@ -0,0 +1,17 @@
+{
+  "analytics": {
+    "page_title": "Analysen",
+    "dashboard_title": "Analyse-Dashboard",
+    "dashboard_subtitle": "Sehen Sie Ihre Shop-Leistungskennzahlen und Einblicke",
+    "period_7d": "Letzte 7 Tage",
+    "period_30d": "Letzte 30 Tage",
+    "period_90d": "Letzte 90 Tage",
+    "period_1y": "Letztes Jahr",
+    "imports_count": "Importe",
+    "products_added": "Hinzugefügte Produkte",
+    "inventory_locations": "Lagerstandorte",
+    "data_since": "Daten seit",
+    "loading": "Analysen werden geladen...",
+    "error_loading": "Analysedaten konnten nicht geladen werden"
+  }
+}

app/modules/analytics/locales/en.json

@@ -0,0 +1,17 @@
+{
+  "analytics": {
+    "page_title": "Analytics",
+    "dashboard_title": "Analytics Dashboard",
+    "dashboard_subtitle": "View your store performance metrics and insights",
+    "period_7d": "Last 7 days",
+    "period_30d": "Last 30 days",
+    "period_90d": "Last 90 days",
+    "period_1y": "Last year",
+    "imports_count": "Imports",
+    "products_added": "Products Added",
+    "inventory_locations": "Inventory Locations",
+    "data_since": "Data since",
+    "loading": "Loading analytics...",
+    "error_loading": "Failed to load analytics data"
+  }
+}

app/modules/analytics/locales/fr.json

@@ -0,0 +1,17 @@
+{
+  "analytics": {
+    "page_title": "Analytique",
+    "dashboard_title": "Tableau de bord analytique",
+    "dashboard_subtitle": "Consultez les indicateurs de performance de votre boutique",
+    "period_7d": "7 derniers jours",
+    "period_30d": "30 derniers jours",
+    "period_90d": "90 derniers jours",
+    "period_1y": "Dernière année",
+    "imports_count": "Importations",
+    "products_added": "Produits ajoutés",
+    "inventory_locations": "Emplacements d'inventaire",
+    "data_since": "Données depuis",
+    "loading": "Chargement des analyses...",
+    "error_loading": "Impossible de charger les données analytiques"
+  }
+}

app/modules/analytics/locales/lu.json

@@ -0,0 +1,17 @@
+{
+  "analytics": {
+    "page_title": "Analysen",
+    "dashboard_title": "Analyse-Dashboard",
+    "dashboard_subtitle": "Kuckt Är Buttek Leeschtungsmetriken an Abléck",
+    "period_7d": "Lescht 7 Deeg",
+    "period_30d": "Lescht 30 Deeg",
+    "period_90d": "Lescht 90 Deeg",
+    "period_1y": "Lescht Joer",
+    "imports_count": "Importer",
+    "products_added": "Produkter bäigesat",
+    "inventory_locations": "Lagerplazen",
+    "data_since": "Donnéeë vun",
+    "loading": "Analysen ginn gelueden...",
+    "error_loading": "Analysedonnéeën konnten net geluede ginn"
+  }
+}